Dosage Equivalents

Sometimes you just need to switch meds. That’s life on the med-go-round. The question frequently comes up, what are the dosage equivalents of various drugs? Are you sure about that prescription your doctor gave you? Is your pharmacist at the HMO completely unresponsive? Here are some starting dosage equivalents for your peace of mind. These work only for the starting dosages. These things aren’t exactly linear, therefore at the higher dosages they don’t exactly map out. So if you’re switching from a high dosage of one to another your doctor is probably writing you a prescription that makes a lot a sense. If you want to try to do the math yourself, see Sheldon Preskorn’s Applied Clinical Psychopharmacology and the NIMH Psychoactive Drug Screening Program. If you ask me how to use those sites, you’re not qualified to use them.

SSRI dosage equivalents: 20mg Celexa (citalopram hydrobromide) = 5mg Lexapro (escitalopram oxalate) = 50mg Luvox (fluvoxamine maleate) = 20mg Paxil (paroxetine hydrochloride) = 20mg Prozac (fluoxetine hydrochloride) = 50mg Zoloft (sertraline hydrochloride) = 75mg of Effexor (venlafaxine hydrochloride). One study has shown that Celexa (citalopram hydrobromide) is the best intermediary drug when rotating SSRIs. Although Effexor (venlafaxine hydrochloride) is not an SSRI, it’s listed here because it is frequently confused for one, its discontinuation syndrome sucks worse than that of the SSRIs’, and at 75mg it affects only serotonin anyway.

Serzone (nefazodone hydrochloride) is not listed here because it mainly reuptakes norepinephrine and is coming off the market anyway. Desyrel (trazodone) also isn’t listed because it really isn’t an SSRI.

For other classes of antidepressants, there aren’t enough in any other class to have those data, or there aren’t enough data available, or I’ve just been lazy. I might take a stab at the TCAs at some point in the future. There are plenty of data on the TCAs. If I get really enthusiastic about this I could come up with something like equivalence between Cymbalta (duloxetine), Serzone (nefazodone hydrochloride) and Effexor (venlafaxine hydrochloride). As well as Strattera (atomoxetine) and Edronax (reboxetine). Remember one of the rules of Crazy Meds – if all y’all bug me about it, it’s not going to happen.

There are no equivalencies across classes. E.g. there’s no dosage equivalent between Prozac and Wellbutrin because they act on different neurotransmitters.

Dosage equivalents for benzodiazepines & miscellaneous tranquilizers & hypnotics: 20mg Ambien (zolpidem tartrate) = 1mg Ativan (lorazepam) = 0.5mg Halcion (triazolam) = 0.5mg Klonopin (clonazepam) = 25mg Librium (chlordiazepoxide HCl) = 20mg Restoril (temazepam) = 20mg Sonota (zaleplon) = 15mg Tranxene (clorazepate dipotassium) = 10mg Valium (diazepam) = 0.5mg Xanax (alprazolam).

Dosage equivalents for atypical antipsychotics, from strongest to weakest: 0.5mg Risperdal (risperidone) = 2.5mg Zyprexa (olanzapine) = 3mg Abilify (aripiprazole) = 20mg Geodon (ziprasidone HCl) = 100mg Seroquel (quetiapine) = you only want to take Clozaril (clozapine) if you’re really messed up and nothing else is going to work. OK, Clozaril (clozapine) works on your brain in a completely different way as well, so there’s not an easy dosage equivalent.

Standard/Typical Antipsychotics – I’ve yet to research that. I don’t know if you can suddenly switch a standard for atypical antipsychotic either.

Dosage equivalents for Anticonvulsants/Old-school Mood Stabilizers – there is no dosage equivalence for most of these meds, as they all act on different parts of the brain. 300mg of Trileptal (oxcarbazepine) = 200mg of Tegretol (carbamazepine), if that’s of any use to you. In theory Depakote (divalproex sodium), Depakene (valproic acid), and all the overseas variants of Depacon (valproate sodium), brand and generic, within the valproate family are dosage-equivalent. In practice you’ll find that they need to be adjusted slightly for each individual’s metabolism, including a switch between brand and generic, so have your blood levels checked after any change. You’ll find the same to be true for all the lithium variants, if you need to switch from one lithium variant to another, even from brand to generic, have your blood levels checked. It’s not in your head if you notice a change. I mean, the effects are in your head, but you’re not imagining things, such changes are real. If your doctor is neither a psychopharmacologist nor a neuropsychiatrist, consult with an experienced neurologist if you need to make a fast switch from one anticonvulsant to another and don’t have the luxury to ease off the first and ramp up the second. The neurologists have more experience dealing with this sort of thing, prescribing the same meds for people with seizures where one med suddenly fails or slams you with a side effect that is too adverse to tolerate and another has to replace it immediately at therapeutic levels. That’s life sometimes in Epilepsyland. Plus the anticonvulsants are very picky when to comes to other meds you might be taking. Anything you take regularly, even non-psychiatric medications, can affect how well they are going to act.

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